STRENGTH OF MATERIALS VIVA PART -1
1. What is hook’s law?
Ans. It states that within the limit of elasticity, the stress-induced (σ ) in the solid due to some external force is always in proportion with the strain (ε ).
2. Define the strength of materials?
The strength of a material is the ability of a material to withstand an applied load without failure or plastic deformation.
3. what is stress? what are the types of stress?
Ans. Resisting force per unit area i.e F/A. When a body subjected to load an internal resistive force arises in the body which causes stress.
Types of stresses: (1) Normal stress (2) shear stress
4. What is the strain? what are the types?
Ans. The strain produces in a body due to a change in its length. The strain is defined as the change in dimension length per unit dimension.
Types of strain: (1) Lateral strain (2) Longitudinal strain (3) Shear strain
5. What is stiffness?
Ans. It is the ability of a material to resist deformation under stress. The modulus of elasticity is the measure of stiffness.
6. What is elasticity?
Ans. It is the property of a material to regain its original shape after deformation when the external forces are removed. This property is desirable for materials used in tools and machines. It may be noted that steel is more elastic than rubber.
7. What is plasticity?
Ans. It is the property of a material that retains the deformation produced under load permanently. This property of the material is necessary for forgings, in stamping images on coins, and in ornamental work.
8. What is ductility?
Ans. It is the property of a material enabling it to be drawn into the wire with the application of a tensile force. A ductile material must be both strong and plastic. The ductility is usually measured by the terms, percentage elongation, and percentage reduction in area. The ductile material commonly used in engineering practice (in order of diminishing ductility) are mild steel, copper, aluminum, nickel, zinc, tin, and lead.
9. What is brittleness?
Ans. It is the property of a material opposite to ductility. It is the property of breaking of a material with little permanent distortion. Brittle materials when subjected to tensile loads, snap off without giving any sensible elongation. Cast iron is a brittle material.
10. What is Malleability?
Ans. It is a special case of ductility which permits materials to be rolled or hammered into thin sheets. A malleable material should be plastic but it is not essential to be so strong. The malleable materials commonly used in engineering practice (in order of diminishing malleability) are lead, soft steel, wrought iron, copper, and aluminum.
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